10. Current or recent (within 12 months prior to screening) participation in research studies involving radiation exposure such that the total research-related radiation dose to the subject in any given year would exceed the limits set forth in the US Code of Federal Regulations (CFR) Title 21 Section 361.1 (http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?FR=361.1))